Talk:Neutering

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Contents 1 More to do 2 NPOV 3 External links 4 Facts in new edits 5 The pics 6 Changing the name of the article 7 A Little More Order 8 questionable facts 9 POV in the Dog article 10 Osteosarcoma Risk 11 FLUTD in castrated vs. intact toms 12 Legal Status 13 Vandalism by User:76.169.127.99 14 Hypothyroidism risk 15 Neutering and Population Control: An Epidemiologic Perspective

[edit] More to do

Whew, set up article, fixed a whole lot of links and redirs, need to now add text about spaying/neutering policies and so on, but I'm out of time. Elf | Talk 23:14, 4 January 2006 (UTC)

Okay, I've put some more meat in the article. A vet or somebody could greatly improve it as well. -- RmM 12:58, 6 January 2006 (UTC)

A request/suggestion. Info on reccomended minimal age for spay/neuter(in cats and dogs) also info on early spay/neuter programs. --Dodo bird 10:06, 26 April 2006 (UTC)

What about explaining the term 'rig' for animals, particularly horses, where the castration has no change in behaviour and neutered animals still behave as if they are intact? Is this the place to cover that? --[User:Nick Wallis]] 12:20, 2 June 2006 (UTC)

The description of Bob Barker's Price Is Right spay/neuter endorsements should be clarified, specifying that he only began making these endorsements in 1981, as explained in Bob_Barker#Animal_rights. --Cybrbeth 16:59, 25 June 2006 (UTC)

[edit] NPOV

I have to question the NPOV status of this article. In every section there seems to be a questioning of the worth of spaying and/or neutering, without much talking about advantages. For example, the health benefits are real, not "theoretical", and "will definitely produce minor personality changes" is without any basis (or source). People often expect their dogs to "slow down" after being neutered, but rarely find that to be the case (in my experience as a vet). Health benefits include elimination of the possibility of pyometra, a common and often fatal disease if not treated, and dogs not spayed by the age of two are seven times more likely to develop mammary tumors.

The section on neutering seems to lead the reader to believe that behavioral reasons for neutering are not worth it, "far from absoute". A closer look at the reference given (a website for Neutersol, a commercial product which is a nonsurgical alternative for neutering - definitely not NPOV - and actually uses as one of its sources its own product insert) shows that neutering gives a greater testosterone reduction and significant effect on mounting, roaming, and urine marking behaviors. The traits not significantly affected are fear and aggression, and I couldn't agree more with that. The source for the part about "poor development of fur" is not cited, but I am familiar with testosterone-responsive alopecia in neutered dogs. It is uncommon, however, and there are also skin problems secondary to testosterone (stud tail).

I do appreciate the point made about no reduced risk of prostate cancer with neutering. That is a common misconception and it drives me crazy when I hear other vets give it as a reason for neutering.

I know I should just shut up and change what I feel is necessary, but I wanted to give everyone a heads up. --Joelmills 05:24, 14 February 2006 (UTC)

Professional input would certainly be appreciated, especially when it comes to sources. I will readily admit that it's very "sketchy" to be sourcing so much information on a single paper associated so closely with a commercial product. However, there is a definite lack of other research on the topic, which, to a great extent, appears to be because a lot of the "facts" (neutering will calm your dog down; neutering will keep your dog from turning into a sex maniac; neutering prevents cancer; etc) are simply taken for granted. I'd be very interested in seeing other research which considers the overall health benefits and risks of S/N. I'm rather sick of seeing references to one particular study which was performed on a dozen or so kittens and came up with the rather obvious conclusion that neutering caused a significant decrease in sexual behavior. (Gee, you think?) Long-term health risks appear to be an understudied topic, which is particularly surprising when one considers that the human equivalents (especially ovariohysterectomy - men generally avoid castration for rather obvious reasons) are generally avoided in the absence of pressing health reasons.

I will also readily admit that I am far from an unbiased source. Had I written this page myself, it'd reflect a strong anti-S/N POV. However, when I first began editing the article, it represented a strongly pro-S/N POV - it read like a shelter's "millions of animals are dying" pamphlet, and in fact cited several such documents as sources.

So yes. Go ahead and change as necessary, with a particular eye to providing alternate academic sources. Zetawoof 09:06, 14 February 2006 (UTC)

Joelmills, go right ahead! The vet's knowledge (longer elaborations in NPOV) is exactly what the article needs. I see there's a whole lot of what could be considered commercial advertisements on the page here, although it's likely they weren't introduced to advertise. I'm probably at least somewhat anti-S/N myself — I do find it somewhat distasteful that there's a legion out there reciting the mantra of spay-spay-spay-spay-spay, ready to repeat the same "facts" when they're pressed for reasons, as though lopping off the genitalia is automatically great and deserves no thought about it. Were it just a process of sterilization, it'd be more sensible. - 194.89.2.39 14:36, 14 February 2006 (UTC)

If the concern about "commercial advertisements" regards the two pharmaceuticals, then that isn't really a major issue. They're both entirely relevant to the discussion, and as far as I know they're more or less unique in the field.

Also, now that you mention it, there doesn't seem to be very much information in the article on simple methods of sterilization (e.g. vasectomy and tubal ligation) - there's a one-line mention of an experimental method of performing a nonsurgical vasectomy, but no mention of the standard surgical method. As far as I know, vasectomies are pretty straightforward in most domestic animals - in some countries, it's even standard practice for some cat breeders to keep vasectomized "teaser toms". It's with tubal ligations that unforeseen issues are said to come up; however, as usual, little research seems to exist... more room for expansion.

What I begin to wonder, however, is whether a move may be in order, as the article is expanding to cover methods of animal sterilization/population control instead of sticking to spaying and neutering. I don't see anything wrong with this expansion; a discussion of spaying and neutering cannot be complete without a mention of their disadvantages and alternatives, so the article naturally expands to cover these related topics. Any suggestions for a broader article title? Zetawoof 19:21, 14 February 2006 (UTC)

I do agree with the fact that there is a compulsion among vets to spay and neuter, and alternatives are rarely discussed. I even once read a study suggesting intact male dogs live longer than neutered ones, but I'll be damned if I can remember where.

I will have to find some good sources on advantages and disadvantages of spaying and neutering. The only source I can think of off the top of my head is a surgery textbook at the office, and you can guess what POV that has. So for now I'll try to expand the article without including sources, but I won't put in anything too controversial. Let me know if I make it too pro S/N. And I think its fine to leave in the Neutersol reference, but I will clarify some of the info coming from their page.

As far as broadening the title, I can't think of a good way to do it at this time. Maybe a separate article for population control in dogs and cats. There is a lot of controversy over trap-neuter-release (TNR) programs for feral cats right now, so I should be able to find some good sources. --Joelmills 20:22, 14 February 2006 (UTC)

The only source I can think of off the top of my head is a surgery textbook at the office, and you can guess what POV that has. Having never read a veterinary surgical textbook myself, I can't say for sure, but I would expect such a source would mostly just cover the mechanics of the procedure itself, and perhaps mention a couple immediate, acute responses that a vet surgeon should check for. It's unlikely to cover longer-term side effects that result from the hormonal changes, which generally don't show up until significantly later. Still, it may be useful.

One thing that I'd definitely like to keep pretty clear in this article is that Neutersol is not significantly different from neutering in its mode of action. Unlike a ZPV (zona pellucida vaccine) for females, its action is more or less a result of its chemically destroying the testes; the differences in results between it and neutering are primarily a result of incomplete destruction of the secretory tissues. As such, it isn't really an alternative to neutering as much as it is an alternate method.

And while I'm mentioning things which I've heard but haven't inserted into the article as a result of a lack of sources, I've also been told that inter-dog aggression involving intact males is generally a result of increased aggression from neutered males toward intact males, rather than vice versa. Is this a documented phenomenon, and does anyone have any idea why?

And yes - please clarify wherever you can! I'm not a veterinary expert, so you're likely to know a lot of details better than I do. Go ahead, be WP:BOLD, and make changes as seem appropriate. If I think you're pushing POV too far in the opposite direction, I'll let you know then. Zetawoof 21:20, 14 February 2006 (UTC)

shouldnt the bullets on the disadvantages be removed? or at least bullets added to the advantages? it seems at first that there are far more disadvantages to neutering than advantages. —Preceding unsigned comment added by 68.188.162.90 (talk) 14:43, 15 January 2008 (UTC)

I definitely oppose the removal of bullet points from that list. When so many effects must be considered, the list format is more readable and more easily understandable than a bit of prose. I would actually support the "Advantages" and "Ambiguous" parts to also be converted into lists.

As for your second point, it would seem that there are more health disadvantages than advantages in males, whereas the health advantages probably outnumber the health disadvantages in females. --128.231.88.7 (talk) 17:52, 21 March 2008 (UTC)

I'm writing to affirm that the article is unnecessarily skewed in favor of leaving animals "in tact." While it might be true that Americans are more into spaying and neutering than Europeans, I don't see how you can run an article on this subject and not point out the extreme immorality of allowing your animal to roam the neighborhood impregnating other people's animals. Or if that's not neutral enough, then it needs to be said that "many, many people would prefer you not allow your male doberman to impregnate their pekinese." Both sides of an issue should be given their due, yes, when both sides have a legitimate argument, but not when one side is issuing utter nonsense. Also, the main reason to neuter a male cat is that there's no living with one who hasn't been neutered. Neutering has entirely changed the personalities of my animals, transforming them from hellions to pets that are a joy to have around. Neutering makes cats MUCH more affectionate and more amenable to training and suggestion. —Preceding unsigned comment added by 208.63.255.236 (talk) 20:40, 2 May 2008 (UTC)

If you find citations from reliable sources (i.e. the scientific literature) that support your points, feel free to add them. As for the idea that neutering male animals is a reasonable approach to population control, please refer to "An Epidemiologic Perspective" further down. Also, the point that neutering cats can make them more easy to live with is covered in both "Advantages" and "Ambiguous".

Besides, this article is about neutering as a veterinary procedure, not about letting one's animals roam free.

--128.231.88.7 (talk) 19:19, 5 May 2008 (UTC)

[edit] External links

I'm going to go ahead and remove the first three external links. Dog hause gives misinformation such as neutering decreasing the risk of prostate cancer and giving the pets longer lives. Spaying/neutering animals says uterine cancer is common, which is not true. Neuter.org is very POV oriented and gives a lot of misinfo, including listing health effects of spaying and neutering such as hypothyroidism, intervertebral disc disease, personality changes, and respiratory disease. Also, Neuter Nazi is just a little too inflammatory, in my opinion.

The last two links, Humane society and Pet rights, aren't perfect, but they balance each other pretty well as far as POV, and Pet rights gives good surgical alternative info. --Joelmills 21:50, 14 February 2006 (UTC)

Good. Very good, in fact. You've got to love this line from the HSUS site, though:

"Doesn't neutering alter an animal's personality? No. Personality changes that may result from neutering are for the better."

So... does it alter personality, or doesn't it? :-)

Anyways, I've done some cleanup on your recent big edit. The diff looks pretty scary, but most of the changes are primarily semantic. The biggest non-semantic change was a mention that cancers of the reproductive organs tend to be relatively rare in animals - otherwise, the assumption is that they're just as common as they are in humans. I also moved some stuff around, placing information on alternatives further down the page. It may make more sense to mention specific methods as an alternative when we talk about a particular operation, though - spaying and Spayvac have more in common with each other than Spayvac and a vasectomy do with each other, for example. And as long as we're talking about moving stuff around, names for spayed/neutered animals probably belong together, too...

Good work, though. This is looking much better. Zetawoof 01:04, 15 February 2006 (UTC)

[edit] Facts in new edits

I think we have this article pretty well cited, so I am going to request that any new edit presenting a new fact also be cited. I'll put something on the user's talk page, and leave the "unspayed dogs have a 25% chance of developing mammary tumors" there for the time being. --Joelmills 03:10, 17 April 2006 (UTC)

What bothers me the most about that claim is the lack of any reference. Is this 25% chance yearly? Over an average animal's lifetime? Does this figure include tumors which never grow large enough to be noticed? If so, how does this affect the claim that "about 50% [...] are malignant"? I'm also a bit peeved that the fact that testicular/ovarian/uterine cancers are generally neither malignant nor common seems to have been removed at the same time that this figure was added - it is not otherwise obvious that testicular cancer (for example) is much less common, and less severe, in animals than it is in humans. I've reworked the sentence to stick this back in. Zetawoof^(ζ) 03:25, 17 April 2006 (UTC)

I'm sure 25 percent is over the lifetime of the dog. It sounds about right by my experience, but I put a request for a cite on the user's talk page. 50 percent malignancy is right, and this is from analysis of biopsied tumors, so yes, it only includes tumors large enough to be noticed, but to my knowledge, that's pretty much all of them. Mammary tumors are not shy. As to the rest of it, the contributer is a new user (and vet from their name), so I would just assume good intentions on their part. --Joelmills 03:35, 17 April 2006 (UTC)

[edit] The pics

A bit too graphic, IMO. Josh 04:55, 11 October 2006 (UTC)

Messy pictures of a messy operation. Zetawoof^(ζ) 05:55, 11 October 2006 (UTC)

I'd have to agree that it's a bit too graphic to have a canine uterus displayed on the page. Sure, that may in fact be the end result, but that picture serves no real educational or informational purpose. Seeing that will make some people uncomfortable, and I hope that's not the goal of putting up that picture.69.207.161.146 17:07, 27 February 2007 (UTC)

That's what it looks like in real life (I've performed the operation more often than I'd care to count). I don't see why this factually accurate picture should be censored. --130.92.9.58 14:10, 1 March 2007 (UTC)

I think that picture does provide useful information, as the anatomy is labeled, but maybe we could use one that is a little less bloody. I'll try to get one soon. --Joelmills 03:57, 2 March 2007 (UTC)

I went ahead and replaced it with a new image, a little less bloody (with the extra bonus of an ovarian cyst). --Joelmills 00:53, 6 April 2007 (UTC)

Nice. Is that midline or side incision? --84.74.129.156 15:27, 8 April 2007 (UTC)

Midline. Sorry that the incision is not shown. --Joelmills 21:35, 8 April 2007 (UTC)

I think we need a side-by-side comparison of a neutered/un-neutered dog.... EvilHom3r 20:07, 30 August 2007 (UTC)

From the back end, I assume? --Joelmills 00:40, 31 August 2007 (UTC)

[edit] Changing the name of the article

I am moving this article to Neutering (and also its discussion section), because spaying is only neutering in females, thus already included in neutering. --Michael Retriever 15:33, 18 November 2006 (UTC)

[edit] A Little More Order

After reading this article, I decided to give some organisation to the part about advantages and disadvantages (I used BE - if someone feels like it, feel free to convert it to AE like the rest of the article). I think that the sources agree that s/n has effects, and IMO, some of them can be classified as positive, some as negative and some as ambiguous, depending on the observer's point of view. This is easier to read and understand than the previous version, where advantages and disadvantages were too often mixed in one sentence.

As a vet, I think that the article in its present state is generally well-researched and respects the NPOV policy. Given that this is a highly controversial topic, we should try and keep our statements backed up with verifyable sources from the peer-reveiwed literature.

As an aside, I also think that it would be interesting to compare the percentual importance of s/n dogs and/or cats in different countries. For example, neutering dogs is a lot more uncommon in Europe than it is in North America (although I unfortunately do not have a numeric source at the moment). Another point that could be added would be a link to a comparison of castration vs. sterilisation as a means of pet birth control. --84.72.116.141 15:56, 7 February 2007 (UTC)

I agree about mentioning the differences in castration frequency between the US and Europe. While I do not have exact number, I've done practice in both regions and definitely saw a difference. AFAIK, some of the Scandinavian countries even consider it illegal without a proper medical indication. Added a phrase about that in the intro; citations welcome. --130.92.9.57 14:56, 25 April 2007 (UTC)

[edit] questionable facts

'In the long run, dogs of both genders have an increased risk of obesity due to the fact that pet owners continue to feed as if the animal was still intact, which can be prevented by modifying the diet.'

removed this as there is no evidence to support it. --80.41.90.45 01:48, 6 March 2007 (UTC)

There is lots of evidence to support this. Consult any good vet surgery textbook. --130.92.9.57 14:04, 6 March 2007 (UTC)

If I recall correctly, most pets today are at risk of obesity due to the fact that we humans don't always understand how much food we should be feeding them, and often don't give our animals enough excersize. In the case of both intact and unintact animals, proper diet and activity would probably fix 99% of overweight animals. I'm not sure that the desexing process really changes their dietary needs THAT much. (I wonder: I think American obesity and over all laziness has increased over the last 30 years, as has awareness of desexing your animals. I wonder if this is a coincidental thing--that pet owners grow more lazy, as more animals are being fixed, and thus, it seems that the populations of desexed animals that are overweight are larger, as there are more and more of them to select from.. No facts or anything, just random thoughts..) —Preceding unsigned comment added by ColbyWolf (talk • contribs) 19:39, 9 April 2008 (UTC)

[edit] POV in the Dog article

The tag on top mentions that a summary of this article is posted in Cat and Dog. This is highly questionable for the cat article, which does not have much information on neutering, which is why I removed the ref. The dog article, however, contains a paragraph on neutering which is strongly POV (pro) and should be adapted to the current version of the article. Since dog is protected, I put a point on it on its discussion page and thought I'd also mention it here. --130.92.9.55 11:49, 15 May 2007 (UTC)

[edit] Osteosarcoma Risk

I have edited the statement regarding the association between neutering and osteosarcoma (OSA) because it was far stronger than the citation, or the literature in general, supports. In a single study of a single breed with a known risk for osteosarcoma far higher than most other breeds, the data showed the total lifetime exposure to sex hormones was negatively correlated with the incidence of OSA. The incidence of the disease was not statistically different between neutered and intact animals overall, though it was different between animals neutered at less than 1 year of age and intact animals. And there is no reason to suggest these findings would support a general relationship between neutering and OSA incidence in other breeds or mixed-breed dogs. Given the questionable clinical significance of the finding (intact animals actually died slightly, though not significantly, earlier than neutered animals overall) and the much more thoroughly demonstrated protective benefits of neutering on life expectancy and other kinds of cancer, I do not find this study sufficient to support a general assertion that OSA risk is a meaningful disadvantage of neutering.

Brennen McKenzie, MA, VMD

Thanks for clarifying that. I thought it sounded a bit strong. --Joelmills 00:45, 18 May 2007 (UTC)

Not quite. There is actually quite a bit more in the literature to support the notion that a correlation between neutering and osteosarcoma exists. I reverted your edit and added a few more refs to support the statement. I could add more, but drew the line at three refs all in all for the time being. The OS risk increase is irrelevant in small dogs given their low overall OS risk, but should be considered in high-risk breeds (the giant breeds and some of the large ones, such as BMD's and - as demonstrated by Cooley et al. - Rottweilers).

If you have articles demonstrating an overall lifespan benefit of neutering, include them under "advantages". Just make sure that they are adjusted for potential confounders, such as the fact that dogs are not neutered at birth and that not all dogs from one birth cohort may have reached the age at which others were neutered, that neutering implies full owner access to veterinary care and the motivation to use it etc.

--130.92.9.55 11:22, 21 May 2007 (UTC) BS, MVM

[edit] FLUTD in castrated vs. intact toms

Under "Ambiguous", the article contains the following phrase:

Contrary to popular belief, neutered male cats are not more prone to urethral blockages than intact toms. A male cat's naturally longer, narrower urethra predisposes the animal for blockage whether it is neutered or not. Key factors in prevention include an increased fluid intake and an adapted diet.[7]

The reference quoted to support this is a lay site (albeit a respectable one), where "studies" are mentioned without giving further references. I've just spent half an hour on Pubmed to research the possibility of such articles existing, but didn't find anything. On the other hand, a predisposition for neutered toms is mentioned in a few textbooks (references to follow). Therefore, I am under the impression that this statement is not sufficiently supported by the literature and would ask to either add better references or to delete it. --130.92.9.56 11:03, 23 May 2007 (UTC)

I just did my own pubmed search, and the only thing I could come up with was PMID 11345305, "Epidemiologic study of risk factors for lower urinary tract diseases in cats", JAVMA 2001 May 1;218(9):1429-35. I read it, and the study concluded that male neutered cats were at increased risk for all types of FLUTD, including urethroliths, urethral plugs, and urethral blockage, and were in fact the most likely group for those. It did not, however, suggest why. Still, whatever the reason, neutered cats are more likely than intact cats to get blocked. A significant contributing factor, in my own opinion, would be the tendency for neutered cats to be indoor cats on dry food. So we may want to take that out of the ambiguous section and put it in the disadvantages section. --Joelmills 02:42, 24 May 2007 (UTC)

I just read through this article and find it very interesting. While I have a few reservations regarding the statistical methods used (notably the lack of a Bonferroni correction), this is typical of such large-database studies. A certain number of the findings can thus be expected to be coincidental. The fact that the findings regarding the increased risk for castrated males are nearly consistent throughout the aetiologies studied and that these results reproduce the ones in the earlier study that the authors quote (Willeberg and Priester, 1976) make me think that it is safe to assume an increased FLUTD risk at least in castrated toms though, and that there is also considerable evidence that the same may be the case for some FLUTD aetiologies in females. Which means that I agree with your last phrase, unless someone can produce something from the literature to back up the current content. --130.92.9.55 11:54, 24 May 2007 (UTC)

All right, I'll wait a couble of days for further comments and then change it. --Joelmills 22:10, 24 May 2007 (UTC)

[edit] Legal Status

May I suggest to add a section about the legal status of S/N to this article? AFAIK, there seems to be a certain increase in mandatory S/N laws in some parts of North America. Some European coutries have also recently adopted mandatory S/N laws for so-called "dangerous breeds". On the other hand, some of the Scandinavian countries prohibit the procedure altogether without a proper medical indication. I think it would be interesting to add information on this to the article. Does someone have sources? --130.92.9.58 11:09, 5 June 2007 (UTC)

One possible source: Unusual facts about Swedish dogs --128.231.88.5 (talk) 14:21, 16 April 2008 (UTC)

[edit] Vandalism by User:76.169.127.99

The said IP has vandalised the link section three times since Sept. 24, 2007. I have left two vandalism warnings on the IP talk page. Should this continue, I will request the IP to be blocked. --130.92.9.55 11:06, 8 October 2007 (UTC)

[edit] Hypothyroidism risk

Regarding the recent addition, the only assertion I'm questioning is the increased risk of hypothyroidism in neutered dogs. My copies of Compendium don't go back that far, and I could only access the abstract online, which didn't mention risk factors. The only other articles I can find are PMID 8175472, which supports the risk, and PMID 10596870, which does not. Thoughts, anyone? --Joelmills 03:00, 7 November 2007 (UTC)

My apologies, I had copied the wrong hypothyroidism reference. This has been corrected in the article. FYI, here is the abstract http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=pubmed&dopt=AbstractPlus&list_uids=8175472 -- Sardog1 07:28, 8 November 2007 (UTC)

Some quotes from the Panciera (1994) paper on hypothyroidism "Spayed female dogs have previously been found to have a higher relative risk of hypothyroidism, compared with sexually intact females [Milne KL, Hayes HM Jr. Epidemiologic features of canine hypothyroidism. Cornell Vet 1981; 71:3-14], and the association of neutering and hypothyroidism found in the present study suggests a cause-and-effect relationship." The paper then goes on to discuss the fact that the direct effect of neutering on thyroid function is mild, but that an indirect effect may be key. "More important in the association between neutering and hypothyroidism may be the effect of sex hormones on the immune system. Castration increases the severity of autoimmune thyroiditis in mice [Okayasu I, Kong YM, Rose NR. Effect of castration and sex hormones on experimental autoimmune thyroiditis. Clin Immunol Immunopath 1981;20:240-245]." -- Sardog1 07:45, 8 November 2007 (UTC)

Thanks for correcting that, it matches the first reference I mentioned above. It was only 66 dogs, however, which isn't that big a sample. On the other hand, the authors felt it was significant, so I won't argue with it. --Joelmills 23:41, 8 November 2007 (UTC)

Milne[1] involved a larger sample of 3206 dogs, and while it found an elevated hypothyroidism risk for both neutered males and spayed females compared to their intact counterparts, in that study the risk was statistically significant only for spayed females vs. intact females. Sardog1 02:41, 9 November 2007 (UTC)

I think that the literature as you quote it would justify including the hypothyroidism risk under "specific to females" rather than under "general". I'll do that now. --84.72.40.134 (talk) 14:42, 22 November 2007 (UTC)

[edit] Neutering and Population Control: An Epidemiologic Perspective

While it does make both statistical and biological sense that spaying females will result in a decrease in the number of litters born, I do not see how castrating males could have that effect. Even in an (illusory) population where 99% of males are castrated, leaving a female in heat unsupervised will still result in a litter of pups/kittens. Why don't animal protection entities promoting neutering focus their limited resources on females, where their efforts actually have a chance of reducing the numbers of new dogs/cats born? --128.231.88.4 (talk) 13:44, 29 January 2008 (UTC)

Because a male animal cannot be everywhere at once. I honestly don't know if cats/dogs suffer the same problem humans do concerning sperm production (that is, in a couple trying to concieve, it's generally recommended then have sex every OTHER night rather then every night, so that his sperm levels will have time to reach reasonable levels again), but it is a logical assumption. More so, in the population of pets, living with humans, castration can curb some of the more undesirable effects of owning a male animal (spraying/marking, mounting behavior, aggression, etc), and it's easier to say "Do this to all of your animals" not just "some" of them.

For groups who catch, fix, and release, it's just better to do it to all animals captured. There isn't always time to ID if it's a male or female. In both cases, the efforts are focused on both because the less viable breeding "couples" there are, the less reproduction that occurs.

Further, in dogs, females only come into heat ever few months. They can only breed once or twice a year. A male dog can breed any time he finds a bitch in season. In cats, it's a bit different. Females go into heat and go in and out of heat every few weeks and continue to do so until they copulate. They ovulate when stimulated to do so, so being mounted and mated biologically 'fools' them into thinking they're pregnant for a few days, then the cycle repeats. I might be wrong about the specifics, but the base facts are pretty correct: In both species, females can only reproduce a few times a year. Males can reproduce year round. There will always be another fertile male/female around. The goal is to remove as many of them as possible from the breeding pool. As much as we'd like, we can't STOP the numbers from rising. There are more every day. So every snip and chop does a bit towards slowing the numbers.

Also, male animals (esp. cats) have been known to kill litters that don't belong to them. if you have 9 fertile males and one fertile female in an area, that female is going to be quite harrassed by said males, and given the numbers, will probably end up loosing her litter every time she has one. She'll go into heat again shortly there after, and the cycle begins anew.

Again, I am not an expert... ColbyWolf (talk) 19:31, 9 April 2008 (UTC)

These statements contain a lot of flawed logic. Spay/Neuter takes more time than determining an animal’s sex. Reproduction rate is controlled by the “bottleneck sex”, which in most mammals is the females – therefore, controlling their reproductive capacity will have more of an effect on the number of litters born. The point that a male dog or cat is able to reproduce all year long is irrelevant, because he can only do it when he finds a female in heat. If there are fewer fertile females around, he will have fewer chances to reproduce. An unsupervised fertile female will in roughly 99.99% of cases receive a “visit” by a fertile male, no matter how low the percentage of intact males in the population is.

Given that animal protection entities lack the necessary funds to neuter all fertile animals in a population, they should concentrate their efforts on females. Neutering males is frankly a waste of money if the goal is population control.

Consider the following scenario: We have 100 males and 100 females and the monetary resources to either spay 70 females or neuter 90 males. If we neuter 90 males and spay no females, the number of litters born will not be significantly affected. However, if we spay 70 females and neuter no males, the number of litters will decrease by roughly 70%.

In the end, it all comes down to the fact that all male fertility is useless for reproduction if there is not enough female fertility available, and that it is much easier to control female fertility than it is to control male fertility in a population. Unless you are able to neuter very close to 100% of males in one population, a single “snip”, even if well-intended, is simply a waste of perfectly good money. With a spay, however, you will see results on population size immediately – even if the operation costs a bit more.

--128.231.88.5 (talk) 15:06, 15 April 2008 (UTC)